Sparking plug



H. L. HALL 2,163,362

SPARKING PLUG Y Filed May 9, 1958 Fig. 1.

Patented -June 20,-1939 l UNITED STATES PATENT OFFICE" 2,163,362 amiamo FLUG nenn muera mul, stratum, renace, England application Mers, 193s, ser-1n No. mss?. In Grece Brunn my z5, 1931 z einen. (c1. 12s-169) This invention relates to sparking plugs and respective parts being such that the inner cenhas for its obje; the .provision of improved tral' element is easily removable from the body means for preventing plugs attaining objection- When cOld but 1S held rmlY in contact therewith ably high temperatures. at working temperatures.

5 Hitherto it has been common practice' to swage In the accompanying drawing Which illustrates 5 on to the mica around the central electrode a this invention: metal sleeve which ensures that the mica is gas- Figure 1 is a Side elevation with the upper half tight at working pressures, provides a convenient in Section 0f One embcdiment, and, means for attaching the central electrode assem- Figure 2 iS e transverse Section 0n line I-I 0f bly to the body of the plug and serves to limit Figurel- 10 the length of mica which is Aexposed to attack Referring t0 the dre-Wing. the body 0f the by the :flames of combustion. plug is provided throughout its entire length with 'Ihe sleeve and body are made of metal with a cylindrical bore 2, the end of said bore at the clearances which prevent them contacting at inner end of the body adjacent the spark gaps working temperatures and therefore the gap bebeing of enlarged diameter and at the point 15 tween themirestrictsthe amount of heat passed where the enlarged bore meets the smaller bore by the sleeve to the body and permits the sur-v a' ilat seating 3 is provided, said seating being faces on either side of the gap to collect heat from disposed at right `angles to the axis. The central the direct attack uponA them of the llames of electrode 4 is of cylindrical formation and is combustion. furnished with a metal sleeve 5 swaged on tothe zo To attain the objects of this invention it is mica insulation 6. 'I'he inner end of the sleeve proposed to form the plug with aninner central 5 which terminates some distance from the head element comprising a central electrode provided l of the central electrode is furnished with a colpractically throughout its entire length with a lar I. The externaldiameterof the sleeve 5 and sleeve of insulation, a metal sleeve swaged on to that of the collar 8 is slightly less than that of 5 the central portion' of said insulation, a collar the respective bores in the body I and the outer surrounding the inner end of said metal sleeve, end of the sleeve 5 is furnished with a screw insulations disposed between the inner face of thread 9. That part of the inner end of the centhe head oi `the central electrode and the inner tral electrode between the head 1 of the central end of the metal sleeve Vand between the outer Velectrode and collar i is Provided with mice in- ,o end of said metal sleeve and the nut on the outer ysulatiou Il, preferably of conical formation as end of the central electrode, an outer plug body, shown, the small end of the cone being disposed the bore in which is provided-with a shoulder'or immediatelybehind the head1, and that part ot Y seating against which the collar surrounding the said central electrode between the outer end of metal sleeve on the inner central element is arthe sleeve 5 and the nut Il is alsoprovided with u ranged to coact, means provided on the outer a sleeve l2 of insulating material. end of said inner central element for drawing When assembling the plug the central element the collar thereon into intimate or gas-tight is inserted into the inner end of the body l, a contact with the shoulder on the body or with a washer Il being disposed between the seating o washer interposed between the two surfaces, the 3 and the collar l. The central element may distance of said shoulder from the inner endot- .now be rmly secured in the body and the collar the plug body being such that when the parts Ydrawn into intimate contact with theseating by are in the assembled position the head of the a nut Il which may, as shown,be formed integral inner central elen'ent is contained within the with a radio-screen Ii. '45 body of the plug whereby the length of said inner For the purpose of preventing any rotative central element exposed to attack by the llames hmovement of the central element within the body, 0f COmbnStiOn iS reducedparticularly when the parts are Ybeing assembled, According to a further feature of this inventhe sleeve l is milled flat to the depth-of the tionthat part of the metalrsleeveon the inner threadasshown at lI,asemi-circularrecess Il central element between the collation the inner is milled'in the end o! the body I and akey Il of w end thereof and the screw threaded portion on corresponding formation is tted in said recess, the outer end thereof is adapted to make contact a clearance being provided between the inner with the body of the plug, said sleeve and body face of the key and the end of the unthreaded being made of'metals having dissimilar co-ef part of the sleeve las shown. nclentsof expansion and the dimensions of the According to a mod iilcatiou the seating 3 in. A ,y

the bodyA may be of conical formation, the coacting face of the collar 8 being formed -to correspond therewith, the coac'ting faces being ground to provide a gas-tight joint. If desired, the collar 8 may be formed separately from the sleeve 5. v Y

The sleeve 5 and the body of thee plug may be made of metals having dissimilar co-eiicients of expansion, the dimensions of the respective parts being so adjusted that they are easily separated when cold but are held irmly in contact with each other at working temperatures.

What I claim is:

1. A sparking plug for internal combustion engines comprising in combination an inner central element composed of a central electrode provided with a head on the inner end and a nut on the outer end thereof and ,practically throughout its entire length with a sleeveof insulation, a metal sleeve swaged on to the central portion of said insulation, a flange surrounding the inner end of said metal sleeve, insulations disposed be- .tween the inner face of the head of the centralelectrode and the inner end of the metal sleeve and between the outer end of said metal sleeve and the nut on the outer end of the central electrode, an `outer plug body, the bore in `Working temperatures.

of the plug body being such that when the parts are in the assembled position the head of the inner vcentral element is contained within the body of the plug whereby the length of said inner central element exposed to attack by the llames of combustion is reduced.

2. A sparking plug for internal combustion engines as claimed in claim 1, in which that part of the metal sleeve on the inner central element between the flange surrounding the inner end thereof and the screw threaded portion on the outer end thereof is adapted to make contact with the body of the plug, said sleeve and body being made of metals having dissimilar coeicients of expansion and the dimensions of the respective parts being sucliv that the inner central element is easily removable from the body when cold but is heid rmly in contact therewith at HENRY LEONARD HALL. 

